Request time out with Django and scikit-image

Question

I am developing a webapp for image processing with scikit-image. Every works fine on both my local machine and on the Amazon EC2 server when I launch the script manually over SSH.

However, when I call my script from Django's views.py every requests fail due to time limit. Basically I launch a request and never get a reply from Django. I am using Apache as web server. I noticed that this happens only if my script import scikit-image, e.g. when I use

from skimage import io

If I remove all import of scikit-image then it works fine (even with dozens of other libraries imported).

Moreover I don't get any error, nor logs so I don't understand where the problem is! Any suggestion?

UPDATE

I tried both the last stable version 0.10.1 and the dev0.11: same problem on both. I noticed that the problem does not appear if I use import skimage or from skimage import img_as_float, img_as_bool but it appears with any of the following and many more

 skimage.color import rgb2hsv
 from skimage.filter import threshold_adaptive
 from skimage.morphology import  remove_small_objects

Answer 1

I finally found the problem and relative solution. The problem relies on the interpreter used by mod_wsgi. Apparently some third party packages for Python which use C extension modules, and this includes scikit-image, will only work in the Python main interpreter. See similar problem here.

For future reference I solved the problem by adding the following line to my site .conf file

WSGIApplicationGroup %{GLOBAL}

Further reference:

• https://code.google.com/p/modwsgi/wiki/ApplicationIssues#Python_Simplified_GIL_State_API
• problem using WSGIApplicationGroup %{GLOBAL} in apache configuration